Recent development in digital technology has made it possible to easily obtain detailed 3D data and high-resolution image data on a measuring object using a laser scanner or a digital photogrammetric technique. For example, a side surface of an object can be precisely measured from the ground, using close-range photogrammetry with a digital camera or using a ground-based measuring instrument.
However three-dimensional data obtained with a measuring instrument that measures the position of, or the distance and direction to, a measurement point (hereinafter simply referred to as “measuring instrument”), such as a laser scanner, an auto-tracking measuring instrument or a non-prism measuring instrument are basically composed of three-dimensional coordinate data including distance data. Therefore, it has become apparent that it is difficult to correlate the 3D data obtained with a measuring instrument with the site conditions, and hence to determine which part of a measuring object has been measured in tying the 3D data to image information of the measuring object, resulting in the complicated formation of a three-dimensional model of the object. Also, when 3D data are obtained with a measuring instrument installed on the ground, 3D data from the air, for example, 3D data on the top of a building or a road from the air, cannot be obtained to make it difficult to form a three-dimensional model of an object.
On the other hand, digital cameras and laser scanners for installation on flying bodies, such as helicopters or airplanes, have been developed in recent years. When images photographed from the air are combined with those photographed on the ground to generate a 3D model of an object, however, a significant amount of image distortion can occur due to the difference in photographing direction, photographing scale or lens aberration, causing a load of image corrections and hence making it difficult to form a three-dimensional model of the object.
The present invention has been made to solve the foregoing problems, and therefore has an objective to provide a model forming apparatus and a model forming method that can simply and efficiently form a three-dimensional model of an object using previously obtained three-dimensional model data of the object as a starting point.
Solving the foregoing problems, the present invention has another objective to provide a photographing apparatus and a photographing method that can efficiently generate a 3D model of an object by correcting images of the object photographed from the air or on the ground.